alt Hacker News> most mould is caused by buildings.
An honourable mention to fitting Cavity Wall Insulation, heavily sold and encouraged by UK government energy saving schemes thorough the 1990's and 2000's.
Except by stuffing the wall cavity, you provide a nice moisture bridge to outside whilst simultaneously stopping air circulating in the cavity and whipping away moisture; thus an explosion of mould.
The policy was a disaster, as getting the stuff removed costs a small fortune.
I think this depends on the construction of the rest of the house. A typical stack built house in the US will have extensive insulation in the exterior walls, but it's paired with a number of different layers intended to expel moisture.
As a retrofit without those things I guess I can see it being problematic.